Integrated circuit memories, such as static random access memories (SRAMs) require increasingly short access times. SRAMs are often used in the portion of a processing system where speed is very important, such as in a cache. Address transition detection (ATD) is one method that has been used to decrease access times. ATD is generally used to provide data line precharge and equalization signals in an integrated circuit memory. However, ATD may also be used for other purposes, such as word line driving, bit line driving, data line sensing, and for data outputting. ATD decreases memory access times by preconditioning the above mentioned circuits, thus allowing a memory access to begin as soon as a change in the address is detected.
In a memory using ATD, an address transition detector provides a pulse in response to an address change. This pulse is used to perform the desired function in the memory, such as precharge and equalization. It is typical to have a separate address transition detector for each address signal for which transitions are to be detected. For example, if a transition of the row address is to be detected, then an address transition detector is commonly used for each row address signal. The output pulses of these detectors are then summed to provide a single pulse. This single pulse is provided when a change in any row address signal is detected.
The access time of a memory using ATD is related to the time it takes to generate an ATD pulse after an address change. The more rapidly an ATD pulse can be generated, the earlier a memory using ATD can be accessed, thus increasing the speed of the memory. However, increasing the speed of the memory usually results in increasing power consumption of the memory as well.